1. Field of the Invention
The invention relates generally to vehicular motion simulation and, more particularly, to an improved seat for inducing motion sensations similar to those experienced during actual operation of a vehicle. The invention is particularly useful in providing sustained acceleration cues and enhancing motion onset cues in an aircraft simulator.
2. Description of the State of the Art
Although simulators for many different types of vehicles have been constructed, to date the principal efforts have been in the field of aircraft simulation. The instant invention will therefore be described in this context.
In present day aircraft simulators, movement is simulated by mounting a full size replica of a cockpit on a large mechanical motion base. The motion base repositions the cockpit replica according to the equations of motion for the particular aircraft being simulated, thereby providing an occupant with kinesthetic information relating to aircraft attitude, velocity and acceleration. Since changes in acceleration are the most noticeable sensations experienced in an actual operational aircraft, motion bases are generally designed to emphasize these portions of the vehicle motion profile.
Owing to various mechanical constraints, motion bases produce the most useful stimuli, or "cues," during the onset phase of low-level, short-term accelerations. However, as the accelerations become larger in magnitude and longer in duration, the limits of the motion system are approached and cue generation is constrained or terminated. A need, therefore, exists for a mechanism capable of producing sustained acceleration cues.
A number of prior art devices have attempted to induce acceleration sensations by body manipulation. These prior art devices reproduce the body position changes which occur during actual accelerations; however, they fail to provide many of the other important motion cues experienced in an operational vehicle. Suffering from such serious shortcomings as seat cushion ballooning, generation of false and conflicting cues, and deterioration of cockpit realism due to the use of cumbersome extraneous hardware, these earlier devices have proven to be of little practical application.
To overcome the problems associated with these prior art devices, the instant inventor, in conjection with two co-workers, previously devised a revolutionary new seat for simulating aircraft motion. Denominated on Advanced G Seat, this earlier invention successfully produced sustained acceleration cues and also enhanced the motion onset cues provided by a motion base.
As described in commonly assigned, U.S. application Ser. No. 521,457, now U.S. Pat. No. 3,983,640 this Advanced G Seat provides the compatible body excursion, flesh pressure gradient and area of contact cues associated with various acceleration profiles, while maintaining cockpit fidelity. The continuing enthusiastic response of flight simulator users to the Advanced G-Seat, has established it as a major breakthrough in the art.
The instant invention significantly improves upon the Advanced G-Seat by incorporating therein means for selectively and independently varying skin tension. The inventor has found that the sensations of flesh surface tension and contraction felt in epidermal regions proximate the seat cushions, during actual vehicular accelerations, and the accompanying variations in force transferred by the clothes to other areas of the flesh, are important motion cues. In an operational vehicle, these cues result from inertail body movement. The instant invention discloses several ingenius mechanisms to reproduce these acceleration effects in a vehicle simulator.
In the previously devised Advanced G-Seat, "scrubbing" along a subject's back resulted from Z axis body shift and lateral upper torso movement. However, this tactile cue occurred merely as an incidental consequence of other drive techniques, required a variation in skeletal attitude, and was limited to the vicinity of the backrest. In the instant invention, skin tension is treated as a separate Haptic System element which can be driven independently, without a change in body position, to produce appropriate tension variations in the flesh surface proximate the seat pan, as well as the backrest.